The main reason why so many people fail to reach the summit of Kilimanjaro is being insufficiently acclimatized to the Kilimanjaro altitude. Standing at 19,341ft above sea-level, Kilimanjaro’s summit falls into the “extreme altitude” category.

Owing to the lack of technical skill necessary to reach the summit, Kilimanjaro has become popular with inexperienced climbers. Coupled with cheap, fly-by-night operators and short treks this can be a deadly combination.

The main point to note is that in order to acclimatize, your body needs TIME. Otherwise you will get sick and have to turn back forfeiting your summit attempt. Or, even worse, you need to be evacuated to hospital.

There is a good reason why the longer routes on Kilimanjaro have a better success rate. They build in enough time for you to rest and acclimatize, giving you the best chance of reaching the summit safely. And without having to suffer the horrible effects of altitude sickness.

People who have a high tolerance for discomfort can be at risk because they push themselves even when they don’t feel well. Of course, a slight headache at altitude can be quite normal.

A result of dehydration, perhaps. You don’t need to be paranoid about it, but you do need to recognize it. And feel comfortable that the guide you are climbing with is keeping a watch on the whole team.

The drug, Diamox, is often recommended by operators, as it can help with acclimatization. The major advantage of using Diamox is that it won’t mask the symptoms of AMS. If you are ascending too rapidly, you’ll still get sick. But Diamox can assist the acclimatization process. It’s a matter of choice whether you decide to take it.

Effects of Kilimanjaro Altitude

Kilimanjaro’s slopes span three altitude categories:

High Altitude 1500 – 3500m, 5000 – 11,500ft

Very High Altitude 3500 – 5500m, 11,500 – 18,000ft

Extreme Altitude 5500m, 18,000ft and above

As we get higher up, the barometric pressure of the air around us decreases. The oxygen contained in the air is the same as at sea level (20.9%). Owing to the decreased air pressure, for any volume of air, there are less molecules of oxygen present. So with every breath, you inhale less oxygen molecules than at sea-level.

At the summit of Kilimanjaro there is 49% less oxygen available than at sea-level.

Typically, your blood’s oxygen saturation is between 95-99%. This is known as SpO2 (Saturation point -Oxygen), as measured by a pulse oximeter (those things they clip on your finger when you are in hospital). As you climb higher, the lower available oxygen will cause your SpO2 to reduce. At the summit it can get as low as 70%, which would be an emergency at sea-level!

Your body doesn’t like reduced oxygen saturation, so it will deploy various efforts to increase it. It is these compensatory changes that the body makes to adapt to the lower-oxygen – ”hypoxic” – environment that is known as “acclimatization” (or “acclimation”).

Acclimatization

Some of the main compensatory changes are as follows:

These you may notice from the first day:

Deeper, more rapid breathing.

Increased pulse rate, even at rest.

Increased blood pressure.

These go on behind the scenes, if your body is given enough time to make the necessary physiological changes (1):

Increased production of hemoglobin (where oxygen is carried in the blood cell).

Reduction of plasma volume making blood “thicker” and increasing the risk of dehydration.

Increased kidney function to excrete excess bicarbonate ions as a result of pH (acid/alkali balance) of the blood changing.

These changes cannot simply happen over night. Your body needs time.

This is why the best summit success rates are had on the longer routes. More importantly than a successful summit, taking a longer route decreases your chances of Acute Mountain Sickness.

Quite simply, the longer it takes to get to the top, the more time your body has to make the changes necessary to operate optimally in the extreme altitude conditions.

Altitude Sickness – Acute Mountain Sickness – can kill you. Most of the deaths on Kilimanjaro are from complications arising from altitude sickness. Continuing higher when your body has failed to adapt to a lower elevation is nothing short of suicidal.

Some people seem to acclimatize very well. It has nothing to do with fitness levels, gender or age. Apart from taking Diamox – which is not a “magic bullet” – to aid acclimatization, there is nothing you can do to speed up the process.

In my opinion, it is important for everyone who attempts Kilimanjaro to do so with an operator who monitors your condition closely. Checking your SpO2 (blood oxygen saturation), your lung sounds (to identify problems early) and use a checklist of how you feel. This should be done once a day at least.

Acute Mountain Sickness

Acute Mountain Sickness – or Altitude Sickness – is the result of climbing to a higher altitude quicker than your body is able to adapt to it. Symptoms can start from around 8,000ft in some people, and in others at around 11,000 ft.

Provided you have no abnormal lung sounds and a good blood oxygen saturation level (SpO2), mild symptoms should normalise after some hours rest. Communication is key – your guides need to be kept up to date with how you feel, and you should not go higher whilst you still have symptoms.

Moderate AMS:

Deterioration of all the above symptoms

Headache worsening

Nausea and vomiting

Increased dizziness

Shortness of breath

Loss of appetite and inability to eat

Very weak and lethargic

Coughing

At this point, you should descend immediately to the elevation where you last felt “well”. Remaining at this lower altitude until your symptoms normalize, only then should you even consider going higher.

If you continue to climb higher with Moderate AMS, you put yourself at risk of needing to be evacuated from the mountain – and worse – you risk your life.

Traveling with a reputable operator, you will not be allowed to get to this point. If you do, then get down that mountain as fast as you are able! Spending some time in a Gamow bag (Portable Altitude Chamber) can be effective to reduce symptoms before making the descent. Under no circumstances should you climb higher after using the Gamow bag.

Severe AMS:

If you somehow managed to ignore the symptoms of moderate AMS, and have deteriorated to the point where you have Severe AMS, then your only hope for your life is to descend as quickly as possible.

Increased shortness of breath

Decreased coordination (ataxia)

Inability to walk

Hallucination and inability to communicate properly

Increased coughing and fluid on the lungs

If you are suffering from severe AMS, it’s very possible that you will not be able to walk down the mountain and an evacuation will be necessary. You probably won’t even know how ill you actually are.

This is where you rely on your guides and team-mates. Keeping an eye on each other, noting if people have symptoms that they seem unaware of. Any reputable operator will have been monitoring your condition long before it gets to this point.
There are two devastating results of severe mountain sickness, HAPE and HACE.

High Altitude Pulmonary Edema (HAPE)

For many years, High Altitude Pulmonary Edema (3) was incorrectly diagnosed as “pneumonia” in various reports of healthy young men dying after a few days at high altitude.

In most cases, some symptoms of Acute Mountain Sickness have preceded the onset of HAPE. Though in some cases it can appear without prior symptoms.

Pulmonary Edema is where fluid builds up in and around the lungs, preventing oxygen from being absorbed and making breathing difficult.

Symptoms of HAPE include:

Productive cough, with blood or mucus

Gurgling lung sounds

Blue lips from lack of oxygen

Extreme fatigue

Tight chest, difficulty breathing

Confusion, lack of coordination

If you are at altitude and have the feeling that you may have a chest infection, assume it is HAPE until proved otherwise.

Symptoms can go from bad to worse very rapidly. Blood oxygen levels will drop, causing the brain to be starved of oxygen. This can lead to the onset of HACE. If oxygen is available it should be given, and descent should be immediate. Waiting around to “see if he/she feels better” will almost certainly result in death.

Descent is the only option, which is further made difficult as exertion can exacerbate HAPE. The shortness of breath and lack of oxygen can make the person unable to walk. For this condition, an evacuation is essential.
It is important to get off the mountain and get medical attention immediately.

High Altitude Cerebral Edema (HACE)

High Altitude Cerebral Edema(4), characterised by a crashing headache that will not go away is the result of a buildup of fluid on and around the brain. The onset can be rapid, and once again, immediate descent is essential.

Symptoms of HACE include:

Confusion and disorientation

Hallucinations

Lack of coordination

Inability to walk

Irrational behaviour (as though the person is drunk)

Severe headache

Coma

Because HACE affects the brain, the person suffering may not know how ill they really are. Treatment with oxygen and a Portable Altitude Chamber whilst preparations are made for immediate descent can help.

Nothing will treat the onset of HACE whilst remaining at altitude. The only option is to go down and seek medical attention immediately.MOST, IF NOT ALL SYMPTOMS OF ALTITUDE SICKNESS ARE AS A RESULT OF ASCENDING TOO QUICKLY TO A HIGH ALTITUDE.(5)

Tips to Stay Safe & Comfortable:

Opt for a longer route, the longer the better.

Do not use cigarettes, sleeping pills or alcohol on the mountain. If you have a headache and need to take a pain-killer, tell your guide.

Choose an operator with robust safety procedures, well trained guides that know how to monitor you and recognize the signs of developing altitude sickness

Communicate with your guides and fellow team-mates, do not “tough it out” if you are feeling unwell.

Keep well hydrated, drinking 3-4 liters of water per day.

Go slowly! This is not a race, and the slower you go, the more your body is able to acclimatize.

For extra safety, choose an operator that carries oxygen canisters and a Portable Altitude Chamber.

If your chosen operator does not carry a pulse oximeter, take one with you – and learn how to use it to monitor your blood oxygen levels.

Consider using Diamox, as recommended by many operators.

Altitude and Pre-Existing Conditions

As discussed in our article How To Choose a Tour Operator, most companies will require a medical form to be filled in prior to being accepted on a trek. This gives them the opportunity to review any current medical conditions you may have and refer you back to your doctor for final acceptance.

If you do suffer from any medical conditions, even if they are well-controlled, it’s worth going to see your doctor or healthcare professional to inquire whether or not it is safe to go to altitude.

A common one is asthma. Many people who have no current symptoms of asthma, but have suffered with it in the past can find it rears it’s head on the mountain. The combination of the dry, cold, dusty air and lack of oxygen can cause attacks.

If you rely on any medications, you should be sure to check with your doctor before attempting the climb. Also check for any interactions with your current medication if you decide to take Diamox.

2 thoughts on “Altitude”

Hi, it is great to read this text. Kilimanjaro has always been my dream, I guess after I read the story of Hemingway. I know somebody who was there and did not like what he told me. Too organized, too prepared, all with chairs all the time. Not my way of going into mountains, but this is unrelated with your text.

I have not been at such altitudes, though I have climbed over 4000. This altitude sickness is totally unpredictable and acclimatization is all one can do. 49% less Oxygen on the summit sounds really frightening. But I would give everything to experience it. Many thanks, you made my day with this text.

I’ve heard that altitude affects everyone differently. I have been as high as 15,000ft and experienced a slight headache, but nothing I couldn’t manage. In preparing for Kilimanjaro, apart from my fitness training, is there anything I can do to help me with the acclimatization process?

Since I’ve been to 15,000ft do you think that means I’m likely to be OK on Kilimanjaro? I understand that going slowly is the key to getting there safely. I’m planning a 7-day route, to give enough time to acclimatize.

Like Scrolling, Eh?

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